Toward the Centre of the Galaxy


Toward the Centre of the Galaxy

From southern latitudes the most amazing region of the sky shines overhead late on austral autumn nights. 

There is no more spectacular part of the Milky Way than the regions around its galactic centre. Or at least in the direction of the galaxy’s core.

We can’t see the actual centre of the Galaxy, at least not with the cameras and telescopes at the disposal of amateur photographers such as myself.

It takes large observatory telescopes equipped with infrared cameras to see the stars orbiting the actual centre of the Milky Way. Doing so over many years reveals stars whipping around an invisible object with an estimated 4 million solar masses packed into the volume no larger than the solar system. It’s a black hole.

By comparison, looking in that direction with our eyes and everyday cameras, we see a mass of stars in glowing clouds intersected by lanes of dark interstellar dust.

The top image shows a wide view of the Milky Way toward the galactic centre, taking in most of Sagittarius and Scorpius and their incredible array of nebulas, star clusters and rivers of dark dust, all located in the dense spiral arms between us and the galactic core.

Starclouds and Stardust – Mosaic of the Galactic Centre
This is a mosaic of 6 segments, each segment being a stack of 4 x 3-minute exposures at f/2.8 with the 135mm Canon L-Series

Zooming into that scene reveals a panoramic close-up of the Milky Way around the galactic centre, from the Eagle Nebula in Serpens, at left, to the Cat’s Paw Nebula in Scorpius, at right.

This is the richest hunting ground for stargazers looking for deep-sky wonders. It’s all here, with field after field of telescopic and binocular sights in an area of sky just a few binocular fields wide.

The actual galactic core area is just right of the centre of the frame, above the bright Sagittarius StarCloud.

Centre of the Galaxy Area
This is a stack of 5 x 5 minute exposures with the Borg 77mm f/4 astrograph and filter-modified Canon 5D MkII at ISO 1600, taken from Tibuc Cottage near Coonabarabran, NSW, Australia.

Zooming in again shows just that region of sky in an even closer view. The contrast between the bright star fields at left and the dark intervening dust at right is striking even in binoculars – perhaps especially in binoculars.

The visual impression is of looking into dark canyons of space plunging off bright plateaus of stars.

In fact, it is just the opposite. The dark areas are created by dust much closer to us, hiding more distant stars. It is where the stars are most abundant, in the dust-free starclouds, that we see farthest into the galaxy.

In the image above the galactic centre is at right, just above the small diffuse red nebula. In that direction, some 28,000 light years away, lurks the Milky Way’s monster black hole.

Milky Way Overhead Through Trees
This is a stack of 5 x 6-minute tracked exposures with the 15mm fish-eye lens at f/4 and Canon 5D MKII at ISO 1600. The trees appear to be swirling around the South Celestial Pole at lower right above the Cottage.

To conclude my tour of the galactic centre, I back out all the way to see the entire sky and the Milky Way stretching from horizon to horizon, with the galactic centre nearly overhead in this view from 3 a.m. earlier this week.

Only from a latitude of about 30° South can you get this impressive view, what I consider one of the top “bucket-list” sights the sky has to offer.

– Alan, April 17, 2016 / © 2016 Alan Dyer / www.amazingsky.com

 

Mosaic of the Autumn Constellations


Mosaic of the Northern Autumn Constellations

I present a horizon-to-zenith panorama of the pantheon of autumn constellations.

Yes, I know it’s winter, but as it gets dark each night now in early January the autumn stars are still front and centre. I took the opportunity during a run of very clear nights at home to shoot a panorama of the autumn sky.

It is a mosaic that sweeps up the sky and frames many related Greek mythological constellations:

• from the watery constellations of Aquarius, Pisces, and Cetus at the bottom near the horizon…

• to Pegasus and Aries in mid-frame…

• on up to Andromeda and Perseus at upper left…

• and finally Cassiopeia and Cepheus at the top of frame embedded in the Milky Way overhead. The Andromeda Galaxy, M31, is just above centre.

Mosaic of the Northern Autumn Constellations (with Labels)

Here, I’ve labeled the participating constellations, though only a few, such as the “square” of Pegasus and the “W” of Cassiopeia, have readily identifiable patterns.

Most of these constellations are related in Greek mythology, with Princess Andromeda being the daughter of Queen Cassiopeia and King Cepheus, who was rescued from the jaws of Cetus the Sea Monster by Perseus the Hero, who rode on Pegasus the Winged Horse in some accounts.

Zodiacal Light brightens the sky at bottom right in Aquarius, and angles across the frame to the left.


 

TECHNICAL:

I shot this from home on a very clear night January 2, 2016 with the Zodiacal Light plainly visible to the naked eye.

This is a mosaic of 5 panels, each a stack of 5 x 2 minute exposures, plus each panel having another stack of 2 x 2 minute exposures blended in, and taken through the Kenko Softon filter to add the fuzzy star glows to make the constellations stand out.

All were shot with the 24mm Canon lens at f/2.8 and Canon 5DMkII at ISO 1600. All tracked on the AP Mach One mount.

All stacking and stitching in Photoshop CC 2015. Final image size is 8500 x 5500 pixels and 3.6 gigabytes for the layered master.

– Alan, January 3, 2016 / © 2016 Alan Dyer / www.amazingsky.com

 

A Panorama of the Entire Northern Milky Way


Panorama of the Northern Milky Way

In a sweeping panorama, here is the entire northern hemisphere Milky Way from horizon to horizon.

This is the result of one of the major projects on my recent trek to Arizona and New Mexico – a mosaic of images shot along the Milky Way over several hours.

The goal is a complete 360° panorama of the entire Milky Way, and I’ve got most of the other segments in previous shoots from Alberta, Australia and Chile. But I did not have good shots of the northern autumn segments, until now.

The panorama sweeps from Cygnus (at top, setting in the western sky in the evening), across the sky overhead in Perseus, Auriga and Taurus (in the middle), and down into Orion, Canis Major, and Puppis (at bottom, low in the southern sky at midnight).

The view is looking outward to the near edge of our Milky Way, in the direction opposite the centre of our Galaxy. In this direction the Milky Way becomes dimmer and less defined. Notable are the many red H-alpha emission regions along the Milky Way, as well as the many lanes of dark interstellar dust nearby and obscuring the more distant stars.

However, a diffuse glow in Taurus partly obscures its Taurus Dark Clouds — that’s the Gegenschein, caused by sunlight reflecting off cometary dust particles directly opposite the Sun and marking the anti-solar point this night, by coincidence then close to galactic longitude of 180° opposite the galactic centre.

Panorama of the Northern Milky Way (with Labels)

Here I provide a guided map of the mosaic. Orion is at lower right, while the Pleiades and Andromeda Galaxy lie near the right edge. The Andromeda Galaxy is the only thing in this image that is not part of the Milky Way.

The bright star Canopus is just rising at bottom, in haze. Vega and Altair are just setting at the very top. So the panorama sweeps from Altair to Canopus.

The sky isn’t perfect! Haze and airglow in our atmosphere add discolouration, especially close to the horizon. In my final 360° pan, I’ll use only the central portions of this panorama.

Now let’s put the horizon-to-horizon panorama into cosmic perspective…

Illustration of the Northern Milky Way Panorama

In this diagram, based on art from NASA’s Spitzer Space Telescope Institute, I show my Northern Milky Way Panorama in perspective to the “big picture” of our entire Galaxy, using artwork based on our best map of how our Galaxy is thought to look.

We are looking in a “god’s eye” view across our Galaxy from a vantage point on the far side of the Galaxy.

Where we are is marked with the red dot, the location of our average Sun in a minor spiral arm called the Orion Spur.

The diagram places my panorama image in the approximate correct location to show where its features are in our Galaxy. As such it illustrates how my panorama taken from Earth shows our view of the outer portions of our Galaxy, from the bright Cygnus area at right, to Perseus in the middle, directly opposite the centre of the Galaxy, then over to Orion at left.

The panorama sweeps from a “galactic longitude” of roughly 90° at right in Cygnus, to 180° in Perseus, over to 240° in Orion and Canis Major at left.

In the northern autumn and early winter seasons we are looking outward toward the outer Perseus Arm. So the Milky Way we see in our sky is fainter than in mid-summer when we are looking the other way, toward the dense centre of the Galaxy and the rich inner Norma and Sagittarius arms.

Yet, this outer region contains a rich array of star-forming regions, which mostly show up as the red nebulas. But this region of the Milky Way is also laced with dark lanes of interstellar “stardust.”

NOTE:

For larger images, see my Flickr site at https://www.flickr.com/photos/amazingsky/

TECHNICAL:

The panorama is composed of 14 segments, most being stacks 5 x 2.5-minute exposures with the filter-modified Canon 5D MkII at ISO 1600 and 35mm lens at f/2.8.

The end segments near the horizons at top and bottom are stacks of 2 x 2.5-minute exposures.

Each segment also has an additional image shot through a Kenko Softon filter to add the star glows, to make the bright stars show up better.

The camera was oriented with the long dimension of the frame across the Milky Way, not along it, to maximize the amount of sky framed on either side of the Milky Way.

The camera was on the iOptron Sky-Tracker. I shot the segments for this pan from Quailway Cottage, Arizona on December 8/9, 2015, with the end segments taken Dec 10/11, 2015. I decided to add in the horizon segments for completeness, and so shot those two nights later when sky conditions were a little different.

— Alan, December 19, 2015 / © 2015 Alan Dyer / www.amazingsky.com

The Wonder-Filled Winter Sky


Mosaic of the Wonder-filled Winter Milky Way

The sky of December contains an amazing array of bright stars and deep-sky delights.

At this time of year we peer out toward the edge of our Galaxy, in the direction opposite to what we see in July and August. Even though we are looking away from the centre of our Galaxy, the Milky Way at this time of year contains a stunning collection of sights – for the naked eye, binoculars or a telescope.

I can’t list them all here, but most are in the lead image above! The image is a mosaic of the northern winter Milky Way, including the brilliant stars and constellations in and around Orion the Hunter.

The Milky Way extends from Perseus in the north at top, to Canis Major in the south at bottom. Throughout the scene are dark lanes and dust clouds, such as the Taurus Dark Clouds at upper right.

The Milky Way is dotted with numerous red “hydrogen-alpha” regions of emission nebulosity, such as the bright Rosette Nebula at lower left and the California Nebula at upper right. The curving arc of Barnard’s Loop surrounds the east side of Orion. Orion is below centre, with Sirius, the night sky’s brightest star, at lower left.

The constellation of Taurus is at upper right and Gemini at upper left. Auriga is at top and Perseus at upper right.

There’s an unusually bright area in Taurus just right of centre in the mosaic which I thought might be an image processing artifact. No. It’s the Gegenschein – a glow of sunlight reflected off comet dust directly opposite the Sun.

Two highlights of this sky that are great regions for binoculars are the Hyades cluster in Taurus ….

The Hyades Cluster with Aldebaran
The Hyades open star cluster in Taurus with the bright star Aldebaran, not a part of the cluster iteslf. The smaller and more distant cluster NGC 1647 is at left. This is a telephoto lens image taking in a field similar to binoculars, and is a stack of 5 x 2.5-minute exposures with the 135mm lens at f/2 and Canon 5D MkII camera at ISO 800, plus two other exposures taken through the Kenko Softon filter to add the star glows. Taken from Quailway Cottage on Dec 7, 2015 using the iOptron Sky-Tracker.

…and the Belt and Sword of Orion.

The Hyades – the face of Taurus – is one of the nearest and therefore largest open star clusters.

Orion the Hunter, who battles Taurus in the sky, contains the famous Orion Nebula, here overexposed in order to bring out the much fainter nebulosity in the region.

The magenta and blue arcs in the image below are photographic targets, but the bright Orion Nebula in Orion’s Sword is easy in binoculars, shining below the trio of his Belt Stars.

Orion Belt and Sword Mosaic
A mosaic of the Sword and Belt region of Orion the Hunter, showing the diverse array of colourful nebulas in the area, including: curving Barnard’s Loop, the Horsehead Nebula below the left star of the Belt, Alnitak, and the Orion Nebula itself as the bright region in the Sword. Also in the field are numerous faint blue reflection nebulas. The reflection nebula M78 is at top embedded in a dark nebula, and the pinkish NGC 2024 or Flame Nebula is above Alnitak. The bright orange-red star at far right is W Orionis, a type M4 long-period variable star. This is a 4-panel mosaic with each panel made of 5 x 2.5-minute exposures with the 135mm Canon L-series telephoto wide open at f/2 and the filter-modified Canon 5D MkII at ISO 1250. The night was somewhat hazy which added natural glows on the stars. No filter was employed here. The camera was on the iOptron Sky-Tracker for tracking but no guiding. Shot from outside Quailway Cottage near Portal, Arizona, Dec 7, 2015. All stacking and stitching performed in Photoshop CC 2015. Stacking done with median combine stack mode to eliminate geosat trails through the fields.

For us in the northern hemisphere, Orion and company are winter sights. But for those down under, in the southern hemisphere, this is the summer sky. So pardon the northern chauvinism in the title!

Either way, on a dark, moonless night, get out and explore the sky around Orion.

TECHNICAL:

I shot the segments for the main mosaic at top on a very clear night on December 5, 2015 from the Quailway Cottage at Portal, Arizona. This is a mosaic of 8 segments, in two columns of 4 rows, with generous overlap. Each segment was made of 4 x 2.5-minute exposures stacked with mean combine stack mode to reduce noise, plus 2 x 2.5-minute exposures taken through the Kenko Softon filter layered in with Lighten belnd mode to add the star glows. Each segment was shot at f/2.8 with the original 35mm Canon L-series lens and the filter-modified (by Hutech) Canon 5D MkII at ISO 1600, riding on the iOptron Sky-Tracker. All stacking and stitching in Photoshop CC 2015. The soft diffusion filter helps bring out the star colors in this area of sky rich in brilliant giant stars.

— Alan, December 11, 2015 / © 2015 Alan Dyer / www.amazingsky.com

Both the Heart and Soul of Cassiopeia


Heart & Soul Nebulas (IC 1805 and IC 1848) in Cassiopeia

Here are both the heart and the soul of Cassiopeia the Queen.

Two days ago I posted an image of the Soul Nebula. Now, here is the matching Heart Nebula, in a mosaic of the glorious region of the Milky Way called the Heart and Soul Nebulas located in the constellation of Cassiopeia.

They are otherwise respectively called IC 1805 and IC 1848. Amid the swirls of nebulosity are numerous clusters of stars, such as NGC 1027 just above centre. The separate patch of nebulosity at upper right is NGC 896.

I shot the frames for this 3-segment mosaic over two nights, with one segment taken from the frames that made up the previous post. Plus I shot two others to span the region of the Milky Way that is about seven degrees long, a binocular field.

Each of the 3 segments is a stack of 12 frames, with each frame a 6-minute exposure. I used the filter-modified Canon 5D MkII and shot through the TMB 92mm apo refractor at f/4.4. All processing was in Photoshop, including the mosaic assembly.

In all, it’s the best image I’ve taken of this much-shot area of the sky. It really brings out the diversity in star colours, and sky colours, from the dusty orange-brown region at left, to the inky dark dustless region at far right.

– Alan, November 18 2014 / © 2014 Alan Dyer

 

The Natural Naked-Eye Milky Way


Centre of the Milky Way Panorama (2011)

In this image I’ve tried to render the Milky Way in a view that simulates what you see with your unaided eyes.

The result is a celestial portrait in subtle shades of black and white.

This is a photo mosaic, but processed contrary to the usual methods – eliminating colour rather than enhancing it, and reducing contrast rather than boosting it. The result is a view that I think quite nicely matches what your eyes see, though certainly from a dark site. And in this case, you would need to be in the southern hemisphere to see this sweep of the Milky Way, from Aquila at left, to the Southern Cross at right, with the bright star clouds around the centre of the Galaxy in Sagittarius and Scorpius in the middle.

I’ve removed colours except for the muted colours of stars. And I’ve tried to render the stars with an intensity and dynamic range that the eye sees but that is often lost in long exposures.

The dark lanes of dust seen here really do look like this under dark skies. The nearby Coal Sack next to the Southern Cross does look a little darker than the rest of the sky. This view also captures another effect you can see in the real sky – the brighter sky below the Milky Way plane beneath Sagittarius and Aquila – there are more stars there, which make the background sky brighter than above the Milky Way plane (along the top of the photo) where the sky is permeated by dark obscuring dust.

This scene also frames the “dark Emu” – the shape drawn in the dark lanes that looks like a flightless emu in the sky. It’s an important “constellation” in Aboriginal mythology in Australia. The emu’s head is the Coal Sack at far right, her neck the long dark lane curving up through Centaurus and Lupus, and her tail the dark lanes at left in Ophiuchus, Scutum and Aquila.

I shot the original images for this panoramic mosaic in Chile in May 2011. You can see the full colour version in my “Milky Way Mosaic” post from 2011. The colours are wonderful. But there’s something enthralling about “capturing” the view more as your eyes – and mind – remember it.

– Alan, February 3, 2013 / © 2013 Alan Dyer